Custom filter for ActiveAdmin.

1_activeadmin_user.rb

ActiveAdmin.register User do
  
  index do
    column :id
    column :full_name, sortable: :last_name
    column :status
    default_actions
  end

  filter :first_name
  filter :last_name
  filter :status_name, label: "Status", as: :select, collection: [:active, :inactive, :invited]

  form do |f|
    f.semantic_errors *f.object.errors.keys
    f.inputs do
      f.input :first_name
      f.input :last_name
      f.input :status
    end

    f.actions
  end

  # Show page
  show title: proc { "#{@user.full_name}" } do |user|
    attributes_table do
      row :id
      row :first_name
      row :last_name
      row :email
    end
  end

end

2_user_model.rb

class User < ActiveRecord::Base
  
  search_methods :status_name
  
  scope :status_name, ->(status) { where("status = ?", status) }

end